Defect marking apparatus



April 27, 1965 T. w. JUDD ETAL 3,180,230

DEFECT MARKING APPARATUS Filed April 9, 1963 4 Sheets-Sheet 1 CONTROLCIRCUIT 3-WAY SOLENOID AIR VALVE WAY SOLENOID AIR VALVE 27 INVENTOR5TYLER w. JUDD B J SEPH M. MANDULA JR- QZ; Q44

ATTORNEY P 1965 T. w. JUDD ETAL 3,180,230

I DEFECT MARKING APPARATUS Filed April 9, 1963 4 Sheets-Sheet 2 (a) 3334 36 ML, 35

d I SCHMITT CONTROL INPUT TRIGGER GATE 442 (f) s| s r 4AL n A V OFF-TIMEFIG. 3 SOLENOID VALVE 2 22l PULSE 2 VARIABLE AMR DEILAY l as PULSELVARIABLE l9 AMP DELAY 2 2 pu INPUT DEKATRON X fi T 2 22? 223 PULSE ZVARIABLE) 208 Ann DELAY 206 3 3 b 207 m8 214 228 $231 PULSE Z VARIABLE-JAMR DELAY i 4 232 4 236"\ fi TIME ADJUST I4 237 235 Y 2 2 RELAY SOLENOIDON-TIME 4 AIR/VALVE E 55$ 7 MV.

238 INVENT'ER.

TYLER w. JU FlG.-4

ATTORNEY April 27, 1965 1-,. w. JUDD ETAL DEFECT MARKING APPARATUS4Sheets-Sheet 3 Filed April 9, 1963 LA JR.

l o .v w Wm? H M mm m L T" wm M a W QE April 27, 1965 "r. w. JUDD ETALDEFECT MARKING APPARATUS 4 Sheets-Sheet 4 Filed April 9. 1963 ATTORNEYUnited States Patent 3,180,230 DEFECT MARKING APPARATUS Tyler W. Judd,Chardon, and Joseph M. Mandala, Jr.,

Cleveland, Ohio, assiguors to Republic Steel Corporation, Cleveland,Ohio, a corporation of New Jersey Filed Apr. 9, 1963, Ser. No. 271,78818 Claims. (CI. 90-15) The present invention relates to the detection ofdefects in metallic workpieces and more particularly relates to anapparatus for marking the location of the defects on the workpieces.

In the manufacture of wire, bars, and other metallic workpieces oneproblem has been the detection of seams and other defects and markingtheir location so they are easily locatable by either visual inspectionor suitable equipment. In the case of heavy workpieces, such as bars, itis often necessary that the marks indicating the location of the defectsshould be readily, visually observable for their subsequent removal tosalvage the bar. In the case of lighter workpieces, such as wire, themark must often be detectable by automatic rejection equipment.

Prior to the present invention, there has not been any satisfactorymechanism to mark the location of the defeet on the workpiece. Priormarking mechanisms are not capable of precision marking; i.e., placingthe mark precisely at the location of the defect. Marks made by priorart mechanisms are not always readily visible, nor are they verypermanent. Moreover, past marking methods do not satisfactorilypenetrate rust, scale, and the like, especially in the case of hotrolled bars. Finally, marks by prior mechanisms are not permanent inthat they do not withstand abrasive handling.

The present invention provides a defect marking apparatus which marksthe location of detected defects in a workpiece. Marks made by thepresent apparatus are permanent and easily visible even though theworkpiece may be subject to abrasive handling. The present defectmarking apparatus includes a rotating cutter of carbide or othersuitable material which is movable to engage the workpiece and cut animpression therein, but which is normally biased out of engagement wtihthe workpiece. An actuator is adapted to move the cutter into theworkpiece for the duration of an energizing pulse introduced into theinput of the actuator. Defect detection equipment is disposed adjacentthe workpiece ahead of the cutter and produces a defect signal each timea defect is detected. The detection equipment and the workpiece arerelatively rotatable such that the detection equipment describes ahelical path around the moving workpiece. A control circuit is connectedto both the detection equipment and the actuator and for each defectsignal received, it introduces an energizing signal to the actuator withthe result that the cutter momentarily engages the worpiece at leastonce for every energizing signal pulse received.

An advantage of the defect marking apparatus of the present invention isthat the cutter only momentarily engages the workpiece to provide asingle short mark rather than a continuous mark for the duration of thedefect. This arrangement increases the life of the cutter. In addition,should the defect detection equipment or other mechanism fail, thecutter will be placed in its non-engaging position spaced from themoving workpiece. This arrangement provides a fail-safe feature so thata mechanism failure never results in a continuous unnecessary out alongthe workpiece. Finally, the duration of the energizing pulse produced bythe control circuit is adjustable to adjust the size of the impressionor the mark made in the workpiece.

3,130,230 Patented Apr. 27, liifiS The operation of the actuator inmarking the location of the defects is controlled by the control circuitin direct relation to the defects detected by the detection equipment.One form of the control circuit is especially suitable for high speedmarking of the location of defects in wire or other similar smallelongated workpieces. When the apparatus of the present invention isused as a wire defect marker, the cutter is caused to engage the movingworkpiece intermittently to provide a plurality of notches for thelength of the defect detected. Where the defect is a long one, acontinuous indication of the defect is necessary. In the latterinstance, a series of notches is more desirable than one long cut,especially if cutter life is to be increased.

Another reason for providing the notch is related to the equipmentprovided for rejecting defective portions of the wire. Such rejectionequipment may utilize an air gage having a die through which the wirepasses. When sound wire passes through the die of the air gage, airpressure is maintained at the die. When the cross-section of the samediameter wire is cut away sufiiciently and the wire is again passedthrough the die, air will leak out of the die causing a measurablereduction of air pressure. The change in air pressure is used to operaterejection equipment. Air gages can sense a notch as small as 0.010 of aninch deep and Axth of an inch long in wire ranging from at least ths to/uil1S in diameter. The control circuit of the wire defect marker of thepresent invention controls operation of the cutter to provide such anotch in the workpiece. In addition, in order to provide accuratelyspaced marks of uniform depth and duration, the control circuit has thefollowing operating characteristics:

(1) The actuator is alternately energized and de-en ergized as long asthe defect signal is received from the detection equipment. Theenergized or on periods and the de-energized or off periods of theactuator may be adjusted to be equal in length.

(2) If the defect signal terminates while the actuator is energized, theactuator remains energized until the completion of its on period.

(3) If the defect signal terminates while the actuator is not energized,the actuator must remain de-energized for at least the duration of itsoff period.

(4) To allow the cutter to precisely mark the longitudinal location of adefect, the control circuit always commences each cycle of operationwith the actuator energized. In addition, the actuator is energized assoon as a defect signal is received, subject to the limitations of item(3) above.

The control circuit of the present defect marking apparatus takes asecond form for marking defects in bars and other large elongatedworkpieces. When the present apparatus is used as a bar defect markerthe cutter rnomentarily engages the workpiece and cuts a slightimpression in the workpiece which produces a shiny mark preferably a fewthousands of an inch deep and %ths of an inch in diameter. This mark isreadily visible and is permanent.

Since the cutter or marker and the defect detection equipment cannot bein the same physical location, the marker is placed behind or downstreamof the detection equipment. Both are preferably placed in a longitudinalline on the same side of the bar. The longitudinal spacing between themarker and the detection equipment is set at a convenient value, e.g.,three inches. The bar travel through the apparatus is helical andforward bar travel per revolution is maintained equal to the spacingbetween the marker and the detection equipment. Upon receiving a defectsignal from the detection equipment the control circuit delays sendingan enample, where a three inch spacing is provided between thedetectorand the marker and the delay period is' approximately .l20.640second depending on bar diameter, it has been found that a maximum offour defects are likely to occur during the delay period. The presentinvention accommodates the additional defect signals during the delayperiod by providing a control circuit having a plurality of time delaycircuits and a counting circuit to sequentially separate the defectsignals into the time delay circuits. The number of time delay circuitsis directly related to the maximum number of defects likely to occurduring the delay period. The outputs of the time delay circuits areconnected to sequentially energize the actuator in a time-spacedrelation identical to the timed spacing of the defects as detected bythe detection equipment. Thus, the present appanatus assures that everydefect detected will be marked;

'Objects and a fuller understanding of the invention may be had byreferring to the following description and claims taken in conjunctionwith the drawings in which:

FIGURE 1 is a schematic diagram of the defect marking apparatus of thepresent invention;

FIGURE 2 is a side elevational view of a part of the apparatus ofFlGd-JRE l;

FTGURE 3 is a block diagram of one form of a control circuit used in theapparatus shown in FIGURE 1;

FTGURE 4 is a block diagram of another form of the control circuit used7 in the apparatus shown in FiG- URE 1; t

FIGURE 5 is a circuit diagram of the control circuit shown in FIGURE 3;and,

FIGURE 6 is a circuit diagram of the control circuit shown in FIGURE 4.

Referring now to the drawings, wherein like reference charactersindicate like or corresponding parts throughout the several views, thedefect markings apparatus of the present invention is indicatedgenerally by the reference character 11. The defect marking apparatus 11includes defect detection equipment 12, a control circuit 13, athree-way solenoid air valve 14, an air cylinder 15, and a cuttermechanism 16. The defect detection equipment 12 is disposed adjacent anelongated workpiece 18 and the two are mounted for relative rotation,the rotating element being determined by the type of detection apparatusused and the nature and size'of the workpiece. The workpiece 13 is shownwith an intermediate portion removed to clearly illustrate details ofthe cutter mechanism 16.

The output defect signal pulse from the detection. 7 equipment 11.2 isintroduced to the input of the control For each defect signal received,

circuit via a line 19. the control circuit 13 will produce at least oneenergizing pulse of adjustable duration. The energizing pulse producedby the control circuit 13 energizes the three-way solenoid air valve 14via a line 2%. When energized, the solenoid air valve 14 allows air toflow into the air cylinder 15 to cause the cutter mechanism to engagethe workpiece 1.8. The cutter mechanism will remain in engagement withthe workpiece for the duration of the energizing pulse introduced to theair valve 14. v

The cutter mechanism 16 includes a carbide cutter 21 which is driven bythe shaft of a high speed motor 22. The motor 22 is continuallyenergized to cause continual rotation of the carbide cutter 21. Themotor 22 is mounted in a ring housing 23 whichpivots on bearings d '24relative to a support base 27. A spring 25 normally biases the carbidecutter in a retracted position spaced from the workpiece 18. The aircylinder 15 includes a piston rod 26 which is connected to a cutterguard 2% on the motor by a shock absorbent material 29.

A guide is secured to the support base 27 to assure accurate positioningof the workpiece relative to the.

cutter when the defect mar-king apparatus is used for wire or othersmall forms of. the workpiece 18. The guide 30 comprises an annularmember having a tapered central hole which is aligned with a hole in avertical wall of the support base 27. An adjustable stop member 3 1 issecured to a bottom wall of the support base 27 and is disposed underthe shaft end of the motor to limit the pivotal movement of the carbidecutter relative to theworkpiece. The guide Sil by positioning theworkpiece 18 and the stop member 31 by positioning the cutter de terminethe depth and size of a mark cut in the workpiece.

i Wire defect marker When the defect marking apparatus 11 is used as awire defect marker, the defect detection equipment 12 operatespreferably on a magnetic field principle. The

efect detection equipment 12 imparts a magnetic field to the workpieceor wire li and detects a seam or other defect by detecting a change inthe strength of themagnetic field. The defect detection equipment 12includes a search probe preferably located near a drawing die 32.

Suitable structure (not shown) is provided to rotate the search probearound the Wire is as the wire passes longitudinally in relation to thesearch probe. Whenever a defect is detected, the detection equipment 12indicates its introduces these'60 cycle signal pulses to the input ofthe control system 13.

The control system 13 of the wire defect marker form of the presentinvention is shown in FIGURES 3 and 5.

As previously noted, FIGURES shows a block diagram of the electricalcontrol system 13. In this control system the 60 cycle defect signal (a)from the detection equipment is introduced to the input of a full waverectiher and filter section 33 via the line 19. The voltage output ofthe rectifier section 33 is a fluctuating D.C. signal which isintroduced to the input of a Schrnitt trigger 34- via a line 35; TheSchmitt trigger 3d transforms the fluctuating DC. signal into a negativegoing rectangular wave shape ([2) of constant amplitude, the duration ofwhich is equal to-the duration of the 60 cycle signal a received fromthe detection equipment. This negative going rectangular wave shape (1))is introduced to first and second gating sections 36, 37 via lines' 3839 respectively.

The rectangular wave shape (b) before it is introduced to the firstgating section 36 is differentiated to form the trigger signaltc) havingnegative and positive going voltage spikes. The first gating section 36is, in effect, normally closed and passes the negative spike to operatean ON-TIME single shot multivibrator 41 via lines 42 43. The negativegoing spike of the trigger signal (c) is a trigger pulse for the ON-TTMEmultivibrator 41 and is indicated by the reference character td). Thecontrol voltage for the first gating section 36 is obtained from theoutput of an OFF-TIME single shot multivibrator 44 via a line 45. When avoltage pulse (.f)'is produced by the OFF-TIME multivibrator 44, it willshift the first gating section 36 from its normally closed state to anopen state.

The rectangular wave shapetb} introduced to the sec 0nd gating section37 is a control voltage for the second gating section and shifts itfrom, inetlect, a normally open a gating circuit 37 is the voltage pulse(1) obtained from the output of the OFF-TIME multivibrator 44 via a line46.

The pulse (d) passed to the ON-TIME multivibrator ll from the firstgating section 36 serves as a triggering pulse so that the output of themultivibrator 41 produces an energizing pulse (g). of adjustableduration, preferably 38 milliseconds. This timed energizing pulse (g) is(one) introduced via a line 48 to a switching circuit 49 to activate thesolenoid air valve 14 for the duration of the pulse, and (two)differentiated and introduced as an initiating trigger pulse (h) to theinput of the OFF-TIME multivibrator 44 via a line 50. At the completionof the 38 millisecond period of the ON-TIME multivibrator 41, thenegative going portion of the differentiated pulse (12) triggers theOFF-TIME multivibrator 44 into operation to produce the pulse (7) of anadjustable time duration, also preferably 38 milliseconds. The voltagepulse (7) is (one) introduced as a control pulse to the first gatingcircuit 36 via the lines 46, 45 and (two) diiferentiated and introducedas an input signal (i) to the second gating section via the line 46. Asa control voltage to the first gating section 36, the voltage pulse (1)shifts the first gating section 36 to, in effect, an open state so thatit does not produce the output trigger pulse (d) as long as the OFF-TIMEsingle shot multivibrator 44 is in operation. At the same time, if thesecond gating circuit 37 is in a closed state because of the presence ofthe 60 cycle signal (a) from the detection equipment, the 38 millisecondpulse (i) introduced to the second gating section 37 will result in anegative going pulse (j) at its output coincident with the completion ofthe OFF-TIME period of the 38 millisecond pulse (1). In other words, thetrigger pulse (j) is time'delayed 38 milliseconds relative to thecompletion of the energizing pulse (g) produced by the ON- TIMEmultivibrator 41. It is pulse (j) which triggers the ON-TIMEmultivibrator to again cause actuation of the solenoid air valve to markthe wire. This cycle will repeat itself as long as the second gatingcircuit 37 is maintained in a closed state by the output of the Schmitttrigger 34. Thus, the carbide cutter 21 will momentarily engage the wirefor approximately 38 milliseconds each time a pulse (g) is produced bythe ON-TIME multivibrator 41 so that a series of equally spaced markswill appear on the Wire over the length of the defect detected.

When the search probe reaches the end of the defect the 60 cycle signal(a) terminates with the result that the second gating circuit 37 opensand prevents further trigger pulses (j) from reaching the ON-TIMErnultivibrator 41. Should the defect terminate and then recur While theOFF- TIME multivibrator is in operation, the first gating section 36 isin the open state and will not pass an initiating trigger pulse to theON-TIME multivibrator 41. This arrangement assures that the off timewill always be the full 38 millisecond period set by the OFF-TIMEmultivibrator.

FIGURE shows the circuit elements of the electrical circuit representedby the block diagram of FTGURE 3. The rectifier-filter section 33includes input terminals 61 which are connected to the output of thedefect detection equipment via line 19 to receive the 115 volt, 60 cycledefect signal. The defect signal is coupled to the rectifier circuit 33by a transformer 62,.the primary of which is shunted by a capacitor 63.The rectifier circuit includes two diodes 64, 65 connected to the outputterminals of the transformer 62 in a conventional full-wave rectifierarrangement. A resistor 66 is connected between a ground connection 67and a center tap on the secondary winding ofthe coupling transformer 62to limit the secondary Winding current. The filter circuit portion ofthe rectifierfilter section 33 includes a parallel combination of acapacitor 68 and a resistor 69 connected between the ground connection67 and the conductor 35 which corresponds to line 35 in FIGURE 3. Apositive voltage is developed across the resistor 69 Whenever an inputsignal is present at the terminals 61. The conductor 35 introduces thispositive voltage to the Schmitt trigger 34 and includes a resistor '70which serves to limit the current introduced to the grid of one section71a of a dual triode tube 71.

The dual triode tube includes two sections 71a, 71!) connected as aSchmitt trigger. The plates of both sections 71a, 71b are connected to apositive 210 v. supply through load resistors 73, '74 respectively. Thecathodes of the tube sections 71a, 71b are connected to the groundconnection 67 through a bias resistor 75. The tube section 71a isnormally cut oil or nonconducting and the tube section 71b is normallyconducting. This is accomplished by connecting the grid of the tubesection 71a to the ground connection 67 via the resistors 70, 69 whilemaintaining a positive voltage on the grid of the tube section 71b bymeans of a voltage divider provided by resistors 76, 77. The resistor 77is connected between the grid of the tube section 71b and the groundconnection 67 and the resistor 76 is connected between the grid of thetube section 71b and the plate of the tube section 71a.

When the positive voltage appearing across the resistor 6? is impressedon the grid of the tube section 71a, this grid swings out of cutoffcausing the tube section 71:: to begin to conduct with the result thatits plate voltage drops. This decrease in plate voltage is transferredto the grid of the tube section 71b through the parallel combination ofthe resistor 76 and a capacitor 7 8 and reduces the current flow throughthe tube section 71b. This reduction in current flow causes bothcathodes to become less positive, thereby increasing the conduction ofthe tube section 71a and further reducing the conduction of the tubesection 71b until the tube section 71b cuts off.

During the time the tube section 71a is conducting, its plate maintainsa constant potential considerably less than the positive 210 v. supplythus giving the negative going rectangular output wave shape (b). Upontermination of the 60 cycle defect signal (a) to the terminals 61, andconsequently of the positive potential applied to the grid of the tubesection 71a, this grid reverts to ground potential causing the currentflow through the tube section 71a to decrease. This results in the plateof the tube section 71a becoming more positive, thereby increasing thepotential on the grid of the tube section 71b with the result that thetube section 71b conducts more heavily. This in turn raises thepotential at the cathodes to cut off the conduction in the tube section71a and returns the Schmitt trigger to its initial stable state. Thenegative going rectangular Wave shape (17) appearmg at the plate of thetube section 71a is dififerentiated by a capacitor 81 in the conductor38, and a resistor 82 before introducing it into the first gatingsection 36. The differentiated signal is introduced to the grid ofsection a of a dual triode tube 80 having two sections 60a, 86bconnected as a parallel cathode-follower gating circuit. The plates ofboth tube sections 80a, 80b are connected directly to a positive 210 v.supply and the cathodes of both sections are connected to a groundconnection 83 through a resistor 84. Initially, the tube section 80a isin a clamped state because of the presence of the resistor 82. The gridof the tube section 8% is connected to the output of the OFF-TIMEmultiviorator 44 via the conductor 45. A resistor 85 is connected inseries with the conductor 45 to limit the control voltage for the firstgating circuit 36 as obtained from the OFF-TIME multivibrator. The tubesection Stlb is in a normally cut-olf or non-conducting state. As longas the tube section 80b remains in a non-conducting state, the negativegoing portion of the trigger pulse (c) applied to the grid of the tubesection 80a appears as the trigger pulse (d) at the cathode of the tubesection 80a due to cathode follower action. This negative going triggerpulse (d) is coupled to the input of the ON-TIME multivibrator 41 by acapacitor 86 in the conductor 42.

Whenever the OFF-TIME single-shot multivibrator is i pulses (f) each ofthese highly positive output pulses is transferred via the conductor 45through the resistor 85 to the grid of the tube section 8%. The positivepulse (7) causes the tube section 891) to conduct heavily and increasesthe cathode potential. Under the latter condition, a signal applied tothe grid of the tube section 8% from the Schmitt trigger will not beable to reduce the potential on the cathodes sufficiently to overcomethe effect of the conduction in the tube section 8%.

Hence, there can be no output trigger pulse (d) from components, andconnections are the same as those of the first gating section 36 exceptthat in this gating section the control voltage is obtained fromtheplate of the tube section 71a in the Schmitt trigger through a resistorQ1 inthe conductor 39. As long as an input control'pulse (b) is receivedfrom the Schmitt trigger the tube section Nib will be cut ofi.

The trigger pulse (i) from the OFF-TIME multivibrator is introduced tothe grid of the tube section 99a via the conductor 46. Because the gridof the tube section 90a is at a highly positive potential, it is notuntil the negative-going spike of the trigger pulse (i) is impressed onit that the second gate 37 will close and trigger the ON-TIMEmultivibrator 4-]. through a capacitor 3. This provides a time delay of38 milliseconds between the triggering of the OFF-TIME multivibrator 44and the triggering of the ON-TIME multivibrator 4-1. Upon termination ofthe 60 cycle signal (a) from the defect detection equipment 12 the plateof the tube section 71a of the Schmitt trigger will attain the positivesupply poential, thus driving the grid of the tube section 9bhighlypositive. The tube section iib then begins to conduct heavily,increasing the cathode potential and returning the second gating circuit37 to its normally open state.

The ON-TIME single shot multivibrator ll includes a dual triode tube 1%having two sections 100a, 1%!) which are connected so as to provide acathode coupled single shot multivibrator. The plates'of the tubesections 196a, limb are connected to the 210 v. positive supple throughresistors Mill, 169% The cathodes of the tube sections 106a, llitib areconnected to the ground connection 33 through a resistor M3. 'The tubesection 100a is normally cut oti or nonconducting and the tube section16% is normally conducting. This is accomplished by connecting the gridof the tube section liiiia directly to ground while at the same timemaintaining a positive potential onthe grid of the tube sectionihtib byconnecting it to the positive 210v. supply through a esistor 1&4 and apoten:

tiometer 105. p

The input trigger pulses (d), (i) from either of the gating circuits 36,37' are introduced to the grid of the tube section ltiilb through one ofthe capacitors as, 93 respectively, a diode 1% and a timingcapacitor W7.'A resistor 108 is provided to hold the cathode of the diode 1% at the210 v. supply in the absence of such input trigger pulses (d), (j). Whentriggered, the grid of the tube section with is driventowards the cutoflpoint, thereby causing a more negative potential to appear on thecathodes of the tube sections lititia, limb. The tube section 1106a thenbegins to conduct causing a further decrease of potential at thegrid ofthe tube section ldiib and holding it below cutofi until thetimingcapacitor ilti'i' can discharge through the resistor 104 and thepotentiometer 1%. When the charge on the timing capacitor 107 hasdecayed sufiiciently,

the grid of the tube section lfltlb swings out of cutoff and' the tubesection 'once again conducts causing the cathode voltage to rise and cutolf the'tube section ltiiia. V

The ON-TIME multivibrator 41 is now initsstable state where it willremain until triggered again by a pulse from either of the gatingcircuits 36', 37. The output, signal of the ON-TiME multivibrator istaken from the plate of the tube section 10% which attains the 210 v.positive supply potential during the time it is cut off which is.

approximately 33 milliseconds preferably. The potentiometer 195 providesa means of adjusting the duration of the output pulse for setting the ontime period.

, The OFF-TIME multivibrator .4 includes a dual triode" tube 110 havingtwo sections ltltia, lltlb which are connected as a cathode coupledsingle shot multivibrator. The circuit functions, components, andconnections of the OFF-TIME multivibrator 44 are the same as those oftheON-TIME multivibrator 41 except no triggering diode is provided. Theoutput pulse (g) of the ON-TIME multivibrator, after beingdifferentiated by a capacitor 111 in the conductor 5%, serves as theinput trigger pulse (11) to. the OFF-TIME multivibrator. A resistor 112is provided in the conductor 56 to attenuate this trigger pulse to theproper amplitude.

The grid of the of a resistor 114 and a potentiometer 115. Therefore, itis not until the'negative going portion of the input pulse (11) isimpressed on the grid ottube section llltib via a timing capacitor 116that the multivibrator 44 will be triggered. Thus, the OFF-TIME singleshot multivibrator will commence its cycle of operation at the instantthat the ON-TTME single shot multivibrator has completed its cycle ofoperation. The output voltage pulse (1) is taken from the plate of thetube section 11012 which attains the positive plate supply potentialduring the time that it is cut off which is also approximatelyGSmilliseconds preferably. The potentiometer. provides a means ofadjusting the duration of the output pulse (f).

The one or more output pulses (f) taken from the plate 7 control grid ofthe tube section 96a.

The switch circuit w includes a tube 121 connected as a switch toactivate the solenoid air valve 14. The tube llzlincludes a control grid122 which is biased by means of voltage divider resistors 123, 124connected from the output of the ON-TIME multivibrator 411 to a negative160 v. supply such that the tube 121 is normally cut off. The tube 121further includes a screen grid 125 which is connected to a positive 300v. supply through a resistor 126. The cathode of the tube 121 isconnected directly to the ground connection 67. The plate of the tube121 is connected to a positive v. supply through the coil of thesolenoid air'valve 14. The coil is shunted by an arc suppressor 127which reduces switching transients.

When the ON-TIME multivibrator 41 is in operation, the plate of the tubesection lltibb is at the plate supply potential, which drives the gridof the switch tube 121 .into clamp causing the tube 121 to conductheavily. This activates the solenoid air valve 14 for aperiod determinedby the duration of the output pulse (g) of the ON-TIME multivibrator.Upon termination of the output pulse (g) the plate potential of the tubesection was reduces grea ly thereby driving the grid 122 of the switchtubellZl below cutoff and die-energizing the solenoid air valve.

Bar defect marker When the defect marking apparatus-is used to markdefects in bars and similar workpieces, the guide 3t and the cutter stop31 are not provided, In addition, the workpiece i3 is positioned aboutone-half inch below the cutter when the motor assembly is in theretracted position. The defect detection equipment 12 operates.

tube section llltib is clamped because I preferably on an eddy currentprincipal as described in United States Patent No. 2,832,040, issued toW. C. Harmon. The defect detection equipment 12 includes a small probecoil which rides on the surface of the bar. The probe coil remainslongitudinally stationary while the bar is propelled beneath the coil ina helical path.

The present bar defect marking apparatus is particularly usable as partof an automatic bar classification equipment. Such bar classificationequipment inspects the moving bars for defects by means of the defectdetection equipment 12 which contains suitable electronic circuitry toclassify the bars into three classes; good, salvage and scrap. Thosebars classed as salvage contain defects which are shallow enough to beremoved without interfering with the intended useof the bar. The defectdetection equipment 12 produces a defect pulse in the form of arectangular wave shape for introduction to the control circuit 13 onlywhen the defect depth is between predetermined maximum and minimumlimits. Thus, the control circuit 13 causes the cutter mechanism 16 tomark the exact location of only those defects which are to be removed tosalvage the bar, all shallow defects less than the minimum limit beinginconsequential and those deeper than the maximum limit rendering thebar unsalvageable. After the defects are marked, the classificationequipment separates the bars into groups of good, salvage, and scrapbars.

As shown in the block diagram of FIGURE 4, the defect pulses from thedetection equipment 12 are introduced via the line 19 to the input of apulse amplifier section 206 where each rectangular pulse is amplifiedand inverted so as to be suitable to drive a dekatron section 207. Aline 208 connects the output of the amplifier section 206 to the inputof the dekatron section 207. The dekatron section 207 includes aplurality of outputs which are connected to the inputs of pulseamplifiers 211-214 via the lines 215-218 respectively. As the defectsignal pulses are introduced to the input of the dekatron section 207,output pulses will appear at its outputs in a sequential relation. Inother words, for the first input pulse introduced to the input of thedekatron section 207 an output pulse will be introduced to the firstamplifier 211, for a second input pulse to the dekatron section 207 anoutput pulse will be introduced to the second pulse amplifier 212, andso forth until the last output circuit 218 is reached so that for thenext input signal an output signal is again introduced to the firstamplifier section 211 and the cycle repeats itself. The dekatron section207, therefore, eifectively acts as a separation circuit to sequentiallyseparate the input signals and introduce them into separate amplifiercircuits where their distinctiveness is maintained during the delayperiod of the control circuit.

Variable time delay circuits 221-224 are connected to the outputs of thepulse amplifiers 21 1-214 via lines 225- 228 respectively. The delayperiods of each of the variable time delay circuits are simultaneouslyadjustable as indicated by the arrows 229-232 respectively. The outputsof all the time delay circuits 221-224 are connected via a mixer circuit234 and a line 236 to the input of an ON-TIME multivibrator 235. TheON-TIM E multivibrator 23-5 produces an output energizing signal of apredetermined duration which is introduced into the input of a relaydriver 237 via the line 238. The relay driver 237 controls energiz-ationof the solenoid air valve .1 4 to cause the carbide cutter 21 to engagethe moving bar for the on-time period set in the multivibrator 235. Thison-time period determines, therefore, the size of the mark made on themoving bar.

Although cfiour separation circuits have been shown in the preferredform of the bar marking circuit, it should be recognized that more orless circuits may be provided depending on the maximum nunrber ofdefects expected to occur :within the time required for one revolutionof the bar.- =Since 'the variable time delays 221-224 operateindependently of each other, all of them can be delaying simultaneouslyto assure marking of all defects that occur within the time period forone bar revolution. Moreover with the sequential separation of thedefect signals from the input pulse amplifier 2%, once a variable delayhas been triggered it cannot be triggered again until each of theremaining variable delays has been triggered. This arrangement allowsample recovery time for the variable delays 221-224.

As shown in FIGURE 6, the input pulse amplifier 2% includes resistors#241, 1222 connected to form a voltage divider which properly biases theinput to a pulse amplifier tube 243. The amplifier tube 243 providessuch amplification and inversion of the input pulse as is necessary todrive the dekatron section 207. The cathode of the tube 243 is connecteddirectly to a ground connection 244. The plate of the tube 243 isconnected through a resistor 245 via conductor 246 to positive 200 v.supply. A capacitor 247 couples the output pulses from the plate'circuit of the tube 243 to the input of the dekatron section 207 viathe conductor 208 which corresponds to line 2% in FIGURE 4.

The input or the dekatron section 257 includes a network of resistors248-250, a capacitor 251 and a clamping diode 252 connected across theresistors 248, 249. The resistor 1250 and the capacitor 251 provide thephase shift necessary to activate the input of a dekatron tube 255. Thedekatron tube 255 includes a pair of guides 256, 257 which arepositively biased by a resistor 25S and a Zener diode .259 connectedbetween the conductor 246 and the ground connection 244. The dekatrontube 255 includes a plate .262 which is connected to a positive 450 v.supply through a resistor 263 which limits the current to the dekatrontube 255.

The dekatron tube 255 also includes twelve cathodes which arerepresented by the encircled numbers 0-11. Every fourth cathode isconnected together so as to provide four outputs from the twelvecathodes. The outputs are represented by the conductors 215-218. Outputload resistors 265-268 are connected between the ground connection 244and the output conductors 215-218 respectively to provide a load on thecathodes. Initially, the cathode indicated by the encircled numeral 0 isenergized and in a state of glow. Each input pulse to the dekatronsection 207 causes this dekatron glow to advance clockwise to the nextcathode. As the glow leaves a cathode, a negative going pulse isdeveloped across its load resistor. For example, the first input pulseto the dekatron tube 255 will cause the glow of the 0 cathode totransfer to the it cathode with the result that a negative pulse isdeveloped across the load resistor 265 connected to the ti cathode. Thisnegative pulse is then introduced to the input of the amplifier circuit211 where it is amplified, shaped and inverted.

Since the four pulse amplifiers 211-214 and the variable delay sections221-224 are identical both with respect to construction and operation,only the pulse amplifier 211 and the variable delay section 221 areshown and described. The input to the pulse amplifier 211 includes acapacitor 271 and a resistor 2'72 connected to form a differentiatingnetwork for the input step pulse introduced by the conductor 215. Theresistor 272 also holds the grid of a vacuum tube 27?: in clamp. Thecathode of the tube 273 is connected to a ground connection 274. Theplate of tube 273 is connected through a load resistor 275 to a positive200 v. supply. The negative input step pulses introduced by theconductor 215 and differentiated by the capacitor-resistor network 271,272 drive the grid of the tube 273 to cutoff, thereby producing a largepositive-going pulse at the plate of the tube 273. This positive-goingpulse is coupled to the input of the delay section 221 through acapacitor 276.

The variable delay section 221 includes tube sections 281, 282 connectedas a cathode-coupled monostable multivibrator. In this multivibrator anearly linear relationship exists between the period of thecathode-coupled,

"in turn, to the tube current.

of the monostable multivibrator and the control voltage applied to thegrid of the normally cut-oil tube section 281. This linearity resultsfrom the fact that the current through the tube section 281 is linearlyrelated to the control voltage, and the duration of the delay islinearly proportional, The linearity of tube current with respect tocontrol voltage is provided by a large cathode resistor 283 whichintroduces negative feedback.

The input of the variable delay section 221 includes a resistor 285which is bypassed by a diode 286. The diode ass serves as a clampingdiode. The input further includes a variable control voltage circuit toadjust the delay periods of the delay section 221. This variable voltagecircuit includes a linear potentiometer 23% which may be remotelylocated for adjustment of the delay period at the operators station.'The potentiometer 238 is connected between a positive 200 v. supply anda ground connection 239 via potentiometers 2%, 2%. The potentiometers290, 291 are provided to adjust the voltage across the potentiometer288m the proper value. The potentiome- V ter 2% includes a slidingcontact 2% which is connected to the lower end of the grid resistor 235of all of the vari able delay sections 221-224 via the conductor 293.This arrangement provides the variable control voltage for each of thedelay sections 221-224. A capacitor 2% connects the conductor 293 to theground'connection 289.

The tube section 282 is normally conducting because of the postivevoltage applied to its grid by a resistor 2% and a potentiometer 297.The conduction of the tube section 282 causes a large voltage to developacross the re sistor 233 which in turn assures that the tube section 281is cut off. The tube section 231 is triggered by applying the positivegoing pulse from the pulse amplifier section 211 to its input. Thispositive going pulse is inverted by the tube section 231 and appears asa negative going pulse at the grid of the tube section 282 because ofthe coupling provided by a timing capacitor 299. This action reduces thevoltage across the resistor 283 which in turn increases the current flowthrough the tube section 281. The tube section 281 is now conducting andthe tube section 282 is cut off. The tube sections 281, 282 will remainin this condition until the timing capacitor 299 discharges somewhatdependent upon the setting of the potentiometer 297 and a potentiometer3% connected between the cathodes of the tube sections 2&1, 2S2.Adjustment of the potentiometers 297, .399 provides for tracking of thefour delay sections 221 224. Thus, it is not necessary that highlyprecise circuit components and vacuum tubes be used. A capacitor 31hbypasses the potentiometer 3% to prevent degeneration during thetransition from one state to another.

The coupling diode 3b? of each of the variable time delay sections221-224 provides isolation of its respective section. The connection ofall the coupling diodes is such that whenever the Ski-TIME multivibratoris in operation the delay sections are isolated from the multivibratoras well as from each other. The output of each variable delay sectionsis connected to the input of the multivibrator section 235 via theconductor'236.

The ON-TIME multivibrators 235 includes the tube sections 3E5, 316connected as a conventional plate coupled monostable multivibrator. Thecathodes of the tube sections 315, 316 are connected directly to aground connection 317. The plates of the tube sections 315, 316 areconnected to a positive 200 v. supply through resistors 318, 319respectively. The plate of the tube section 315 is also connected to thegrid of the tube section 316 through a capacitor 32a, and the grid ofthe tube section Sid is connected to the positive 200 v. plate supplythrough a resistor 321 and a potentiometer 322. The constants of thecapacitor 320, the resistor 321, and the potentiometer 322 determine theon-time period of the multivibrator 235.

The relay driver and relay section 237 includes a tube section 325 whichcontrols energization of a relay coil 326. The grid of the tube section325 is D.C. coupled to the plate of the tube section 316 via a resistor327 and a capacitor 328. The grid of the tube section 325 is connectedtoa negative v. supply through a resistor 329. The resistors 327, 329form a voltage divider which normally biases the tube section 325 to cutoif. When the ON-TIME multivibrator 235 commences operation during itson-time period, the grid of the relay driver tube 325 is'drivenpositively causing it'to conduct heavily. The

conductive state of the relay driver tube 325 permits curswitchingtransients.

In conclusion, the present invention may be described as an apparatusfor marking defects in moving workpieces and comprising essentially aworkpiece marking element, an actuator to move the marking element intoengagement with the moving workpiece, a defect detection instrumentdisposed adjacent. the workpiece and producing a defect signal'for eachdefect detected, and a control circuit connected to the actuator and tothe defect detection instrument and transmitting energizing signals tothe actuator in a predetermined relation to the defect signals receivedfrom the detection instrument. form the control circuit produces aplurality of equally spaced, timed energizing pulses for the duration ofeach defect signal so that a plurality of marks are made over the lengthof each defect. In another form thecontroi circuit delays production ofthe energizing signal until a predetermined time after receiving thedefect signal so that the mark falls exactly on the location of thedefect. The latter control circuit also accommodates all the defectsignals received during each delay. period so that every defect detectedis marked.

Although the invention has been described in its preferred form Withacertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of partsmay be resorted to Without departingfrom the spirit and the scope of the invention as hereinafter claimed.

' What is claimed is:

1. An apparatus for marking the location of defects in a longitudinallymoving workpiece, said apparatus comprising: V i

(a) a defect marker movably mounted for movement between a markingposition engaging the workpiece and a retracted position spaced from theworkpiece; (b) actuator means operatively connected to said defeetmarker for movingit to the marking position in response to an energizingsignal; (c) defect detection means disposed adjacent said workpiece,said detection means having an output producing a defect signal for theduration of each defect detected; and,

(d) control means having an input connected to the In one a 13 producingat its output a plurality of energizing signals of predeterminedduration and spacing so that said marker is caused to mark the movingworkpiece intermittently for the duration of the defect detected.

2. An apparatus for marking the location of defects, in a longitudinallymoving workpiece, said apparatus comprising:

(a) a defect marker movably mounted for movement between a markingposition engaging the workpiece and a retracted position spaced from theworkpiece;

(b) actuator means including energizable and movable elements, saidmovable element being connected to said defect marker and adapted tomove it to the marking position whenever an energizing signal isintroduced to the energizable element;

() defect detection means disposed adjacent said workpiece, saiddetection means having an output producing a defect signal for theduration of each defect detected; and,

(d) control means having an input connected to the output of the defectdetection means and an output connected to the energizable element ofthe actuator means, the output of said control means producingenergizing signals of predetermined duration and spacing in response toa defect signal introduced at its input, and the number of saidenergizing signals per each defect signal being proportional to thenumber of times the duration of the defect signal is divisible by thepredetermined duration and spacing of one energizing signal.

3. Anapparatus for marking the location of defects in a longitudinallymoving workpiece, said apparatus comprising:

(a) a defect marker movably mounted for movement between a markingposition engaging the workpiece and a retracted position spaced from theworkpiece;

(b) actuator means including energizable and movable elements, saidmovable element being connected to said defect marker and adapted tomove it to the marking position whenever an energizing signal isintroduced to the energizable element;

(0) defect detection means disposed adjacent said workpiece, saiddetection means having an output producing a defect signal for theduration of each defect detected;

(d) a pulse forming means having an input connected to the output ofsaid detection means, and an output producing an energizing pulse ofpredetermined duration each time a signal is introduced into its input,said output being connected to said energizable element to energize itwith said energizing pulse;

(e) a gating circuit having an input connected to the output of saiddetection means, an output connected to the input of said pulse formingmeans, and a control, said gating circuit being normally closed andpassing to its output the defect signals received at its input, and saidgating circuit being open whenevera control pulse is applied to itscontrol so that the defect signals do not pass to its output; and,

(f) delay circuit means having an input connected to the output of thepulse forming means and an output connected to the control of the gatingcircuit, said delay circuit means producing a control pulse at its 7output a predetermined time after receiving an energizing pulse at itsinput.

4. The apparatus of claim 3 including, incombination:

(g) said pulse forming means including means to adjust the duration ofthe energizing pulse; and,

(It), said delay circuit means including means to adjust the duration ofsaid control pulse whereby the longi- Y tudinal length of the marks onthe moving workpiece is set by the adjusting means of the pulse formingmeans and the spacing between the marks is set by the adjusting means ofthe delay circuit means.

5. An apparatus for marking the location of defects in 14 alongitudinally moving workpiece, said apparatus comprising:

(a) a defect marker movably mounted for movement between a markingposition engaging the workpiece and a retracted position spaced from theworkpiece;

(b) actuator means including energizable and movable elements, saidmovable element being connected to said defect marker and adapted tomove it to the marking position whenever an energizing signal isintroduced to the energizable element;

(0) defect detection means disposed adjacent said workpiece, saiddetection means having an output producing a defect signal for theduration of each defect detected;

(d) a first single-shot multivibrator having an input,

and an output producing an energizing pulse of predetermined durationeach time a signal pulse is introduced into the input, said output beingconnected to said energizable element;

(e) a normally closed first gating circuit having an input connected tosaid detection means, an output connected to the input of thesingle-shot multivibrator and producing a signal pulse whenever a defectsignal is applied to its input, and a control, said first gating circuitbeing open whenever a control pulse is applied to its control so thatsaid signal pulse is not produced by its output;

(f) a second single-shot multivibrator having an input connected to theoutput of the first multivibrator, and an output producing a triggerpulse of predetermined duration at the termination of each energizingpulse received from the first multivibrator; and,

(g) a normally open second gating circuit having an input connected tothe output of the second multivibrator, an output connected to the inputof a first multivibrator, and a control connected to the output of thedetection means, the output of said second gating circuit being a signalpulse coincident with the termination of the trigger pulse introduced toits input whenever a defect signal is introduced to its control.

6. An apparatus for marking the location of defects in a longitudinallymoving workpiece, said apparatus comprising:

(a) a defect marker movably mounted for movement between a markingposition engaging the workpiece and a retracted position spaced from theworkpiece;

(b) actuator means including energizable and movable elements, saidmovable element being connected to said defect marker and adapted tomove it to the marking position whenever an energizing signal isintroduced to the energizable element;

(0) defect detection means disposed adjacent said Work piece, saiddetection means having an output producing a defect signal for theduration of each defect detected;

(d) trigger circuit means having an output producing a defect signalpulse having a duration equal to the duration of the defect signal;

(e) a first gating circuit having an input, an output,

and a control;

(1) dififerentiating circuit means connecting the input of said firstgating circuit to the output of said trigger circuit and differentiatingthe defect signal pulse to form a trigger pulse coincident with theleading edge of the defect signal pulse;

(g) said first gating circuit being, in effect, normally closed so thatwhen no control signal is applied to its control, its output produced atrigger pulse similar to that introduced to its input;

([1) a first single-shot multivibrator having an input connected to theoutput of the first gating circuit and an output producing an energizingpulse of predetermined duration in response to each trigger pulseintroduced to its input;

' tion:

prising:

r (i) means connecting the output of said first multia vibrator to theenergizable element of said actuator means so that said marker engagesthe moving workpiece for the duration of each energizing pulse;

(j) a second single-shot multivibrator having an input,

gizing pulse to form a trigger pulse coincident with r the trailing edgeof said energizing pulse;

(1) a second gating circuit having an input connected to the-output ofsaid'second multivibrator, an output connected to the input of the firstmultivibrator, and a control connected to the'output of said triggercircuit means; 7 V v (m) said second gating circuit includingdifferentiating means to form a trigger pulse at the output of thesecond gating circuit coincident with the trailing edge ofeach-p ulseintroduced to its input; and,

(11) said second gating circuit being, in etfect, normally open andproducing trigger pulses at its output only for the duration of a defectsignal pulse introduced at its control. V 7. The combination of claim 6,including, in combina- (0) said detect marker including a rotatingcutter adapted to make an impression in the workpiece when said defectmarker is in the marking position.

8. An apparatus for marking the location-of defects in a longitudinallymoving workpiece, said apparatus comprising:

(a) a defect marker movably mounted for movement between a markingposition engaging the workpiece and a retracted position spaced from theworkpiece;

(b) actuator means including energizable and movable elements, saidmovable element being connected to said defect marker and adapted tomove it to the marking position whenever an energizing signal isintroduced to the energizable element; 7

(c) defect detection means disposed adjacent said work piece and aheadof the defect marker relative to the moving workpiece, said detectionmeans including an output producing a defect signal for each defectdetected;

(d) a counting circuit having an input and a plurality of outputs, saidinput being connected to the output of said detection means; I r

(e) saidcounting circuit passing the defect signals sequentially to itsoutputs;

(f) a like plurality of delay circuits each having an input connected toa ditferent output of the counting circuit, the delay period of eachdelay circuit being the time it takes a point on the workpiece to movefrom the detection means to the defect marker; and,. I

(g) a pulse forming means having an input connected 7 to the outputs ofall the delay circuits and an output connected to said energizableelement, said pulse forming means producing an energizing pulse at itsoutput in response to, each defect signal introduced at its input, 7 9.The apparatus of claim 8 wherein the number of d lay circuits isproportional to the maximum number of defects expected to be encounteredduring a single delay period. 1 v o 10. The apparatus of claim 8including-in combination:

(h) said pulse forming means including means to adjust the duration ofthe energizing pulse.

11. An apparatus for marking the location of defects I in alongitudinally moving workpiece, said apparatus comdefect markermot/ably mounted for movement marking position Whenever an' energizingsignal is introduced to the energizable element;

(c) defect detection means disposed adjacent said workpiece and ahead ofthe defect marker relative to the moving workpiece, said detection meansincluding an output producing a defect signal for each detect detectedWhere a maximum number of N defects are likely to occur in the timeperiod it takes 7 for a point onrthe workpiece to move from saiddetection means to said defect marker;

(d) a counting circuit including a multi-cathode counting tube having aguide grid means, saidv guide grid means being connected to the outputof said detection means; i V

(e)'every Nth cathode of said counting tube being connected together toprovide N outputs;

(f) N delay circuitseach having an input and an output, the inputs beingconnected'to a different output of the counting tube; V

(g) the delay period of each delay circuit being said time period for apoint on the workpiece to move from the detection means to the defectmarker; and,

(h) a single-shot multivibrator having an input connected to the outputsof all the delay circuits and an output connected to said energizableelement, said multivibrator producing an energizing pulse ofpredetermined duration at its output in response to each defect signalreceived from the delay circuits.

12. The apparatus of claim 11 including, in. combination: i j i (i saiddefect marker including a rotating cutter adapted to make animpressionin the workpiece when said defect marker is in the markingposition;

13. An apparatus for marking the location of defects in a travelingworkpiece comprising:

(a) guide means for establishing a longitudinal path of workpiecetravel; a

(b) adefect marker including a rotating cutter adapted to cut apermanent impression in a workpiece, said cutter being mounted formovement between a marking position projecting into 'the path of travelfor engaging a workpiece and a retracted position spaced from the pathof travel;

(0) means urging said cutter toward one of said positions; 7

(d) actuator means operatively connected to said cutter for moving it tothe other of said positions in response to an energizing signal;

(a) defect detection means disposed adjacent said path of travel, saiddetection means having an output for producing a defect signal inresponseto a defect detected in a workpiece; (7) control means having aninput connected to the output of said detection means andan outputconnected to said actuator means, said control means producing anenergizing signal at'its output in response to a defect signal receivedat its input whereby said actuator means fmoves said cutter to saidother means and thestop means whereby the depth of the impression madeby said cutter may be adjusted and set at a predetermined depth. 7

14. The apparatus of claim 13 including, in'combination;

(h) an adjustment means interposed between the guide 1 7 (i) saidcontrol means including means to adjust the 1 duration of saidenergizing signal so that the length of the mark may be adjusted.

15. The apparatus of claim 14 including, in combination;

(j) said detection means and said workpiece being relatively rotatableso that said detection means describes a helical path around saidworkpiece as said workpiece travels relative to said detection means.

16. An apparatus for marking the location of defects in a longitudinallymoving workpiece, said apparatus comprising:

(a) a base including means for establishing a longitudinal path ofworkpiece travel;

(b) a defect marker including a rotating cutter adapted to cut apermanent impression in a workpiece, said cutter being mounted formovement between a marking position projecting into the path of travelfor engaging a workpiece and a retracted position spaced from the pathof travel;

() means urging said cutter toward one of said positions;

(d) actuator means having an energizable element and a movable elementoperatively connected to said cutter and adapted to move said cutter tothe other of said positions when an energizing signal is introduced tosaid energizable element;

(e) I a defect detection device disposed adjacent the path of workpiecetravel, said device and the workpiece being relatively rotatable so thatone moves helically relative to the other as the workpiece moveslongitudinally;

(i) said defect detection device being spaced ahead of the cutterrelative to the moving workpiece, the space between the defect detectiondevice and the cutter being substantially the distance of longitudinaltravel of the workpiece for one relative revolution of the workpiece andthe detection device;

(g) said defect detection device having an output producing a defectsignal for each defect detected;

(h) a control circuit having an input connected to the output of saiddetection device and an output connected to the energizable element ofsaid actuator means;

(i) said control circuit producing an energizing signal at its outputfor each defect signal received at its input;

(j) said controlcircuit including means to adjust the duration of saidenergizing signal whereby the length of the mark cut in the workpiecemay be adjusted by adjusting the time duration of the energizing signal;and,

(k) said control circuit including adjustable time delay means to delayeach energizing signal relative to its corresponding defect signal for aperiod of one revolution of the workpiece relative to the detection de-18 vice whereby the cutter may be caused to engage the workpiece at thelocation of the defects detected by said detection device. 17. Anapparatus for marking the location of defects in a longitudinally movingworkpiece, said apparatus comprising:

(a) a defect marker movably mounted for movement between a markingposition engaging the workpiece and a retracted position spaced from theworkpiece;

(b) actuator means connected to said defect marker and adapted to movesaid defect marker to a marking position whenever an energizing signalis introduced to an input of the actuator means;

(0) defect detection means diposed adjacent said workpiece and ahead ofthe defect marker relative to the moving workpiece, said detection meansincluding an output producing a defect signal for each defect detected;

(d) separation circuit means having an input and a plurality of outputs,said input being connected to the output of said detection means, saidseparation circuit means effectively passing the defect signals receivedat its input sequentially to its outputs;

(e) a like plurality of individual delay circuits each having an inputconnected to a different output of the separation circuit means, delayperiods of the delay circuits being substantially the time it takes apoint on the workpiece to move from the detection means to the defectmarker; and,

(f) energizing pulse producing means having an input connected to theoutputs of all the delay circuits and an output connected to the inputof said actuator means, said pulse producing means producing anenergizing pulse at its output in response to each defect signalintroduced at its input whereby the distinctiveness of the defectsignals received by the separation circuit is maintained.

18. The apparatus of claim 17 wherein the defect detection means and theworkpiece are relatively rotatable and one moves helically relative tothe other, the detection means is located ahead of the defect marker adistance equal to the amount of workpiece travel per revolution wherebythe delay periods of the delay circuits are the period required for onerevolution of the workpiece relative to the defect detection means.

References Cited by the Examiner UNITED STATES PATENTS WILLIAM W. DYER,JR., Primary Examiner.

1. AN APPARATUS FOR MAKING THE LOCATION OF DEFECTS IN A LONGITUDINALLYMOVING WORKPIECE, SAID APPARATUS COMPRISING: (A) A DEFECT MARKER MOVABLYMOUNTED FOR MOVEMENT BETWEEN A MARKING POSITION ENGAGING THE WORKPIECEAND A RETRACTED POSITION SPACED FROM THE WORKPIECE; (B) ACTUATOR MEANSOPERTIVELY CONNECTED TO SAID DEFECT MARKER FOR MOVING IT TO THE MARKINGPOSITION IN RESPONSE TO AN ENERGIZING SIGNAL; (C) DEFECT DETECTION MEANSDISPOSED ADJACENT SAID WORKPIECE, SAID DETECTION MEANS HAVING AN OUTPUTPRODUCING A DEFECT SIGNAL FOR THE DURATION OF EACH DEFECT DETECTED; AND(D) CONTROL MEANS HAVING AN INPUT CONNECTED TO THE OUTPUT OF THE DEFECTDETECTION MEANS AND AN OUTPUT CONNECTED TO THE ACTUATOR MEANS, SAIDCONTROL MEANS, IN RESPONSE TO A DEFECT SIGNAL INTRODUCED AT ITS INPUT,PRODUCING AT ITS OUTPUT A PLURALITY OF ENERGIZING SIGNALS OFPREDETERMINED DURATION OF THE DEFECT DETECTED.